The present invention relates generally to improved devices and methods for the delivery of laser energy within a mammalian subject and, more specifically, to fiber optic guidewires and methods of using same.
Angioplasty and atherectomy are therapeutic medical procedures in which a catheter or the like is inserted into a blood vessel to increase blood flow. In such procedures, a steerable guidewire of relatively small diameter is typically inserted into the patient's blood vessel and moved into proper position past the obstruction. Then a larger treating catheter, as some examples only, a balloon catheter or a laser catheter, is advanced along the guidewire until the catheter is in proper position. The guidewire makes it easier to position the catheter relative to the target site. The catheter is then operated to accomplish its intended purposes. When the catheter and guidewire are withdrawn, the previously obstructed area remains dilated, and blood flow in the target area is increased.
Catheters containing optical fibers transmit energy to irradiate internal parts of the body for diagnostic and therapeutic purposes. There are many medical applications in which it is desirable to deliver energy, such as laser energy, through an optical fiber or similar waveguide device disposed in a body cavity for treatment or diagnosis. These include, among others, the ablation of tissue such as plaque and tumors, the destruction of calculi, and the heating of bleeding vessels for coagulation. The lasers used may produce either pulsed or continuous-wave light of wavelengths ranging from the ultra-violet to the infra-red.
Although a laser catheter can ablate the occlusion, its relatively large diameter sometimes prohibits adequate positioning within the vessel to perform the ablation. Moreover, in some situations, such as with chronic total occlusions, the shape and nature of the vascular occlusion may not permit a guidewire to be positioned so that a laser catheter can be inserted to perform the ablation.
Current mechanical guidewires are limited to mechanical forces transferred to the tip of the device through the shaft in order to create dissections within the vascular occlusions. These mechanical guidewires often cannot cross or penetrate lesions that are often highly calcified in nature, and they do not employ laser energy to facilitate the crossing of vascular lesions. Thus an unmet need remains for a guidewire system that can consistently penetrate and cross chronic total occlusions within the mammalian vasculature with suitable stiffness and torque characteristics.
Embodiments of the present invention provide solutions to at least some of these problems.